Resiliently urged clamps are convenient for a number of purposes where a member has to be retained in position temporarily, or even over an extended period of time if periodic adjustment of the position is required. One typical such application is that referred to above, namely that of retaining a skirt rubber for a conveyor belt. Skirt rubbers are laminar elements which define a volume about a moving conveyor belt to retain bulk materials being conveyed thereon, and therefore have one edge in contact with the moving belt which gradually wears in use. For this reason it is necessary to be able to adjust the position of the skirt rubber to take up the wear after a period of service. Conveyor belts for bulk material are typically used in the mining or minerals processing industries, and the environment of the conveyor is frequently contaminated with aggressive chemicals so that any clamp utilising accurately formed components having a high tolerance or close moving parts is liable to failure due to corrosion. One known skirt rubber clamping device involves the use of a resilient rubber bush which can be stressed in torsion to apply the required turning moment about a clamping lever arm. One disadvantage experienced with such bushes, however, is a fact that, because they are static but under load throughout their working life the resilient material can acquire a "set" gradually losing the torsional biasing force until the skirt rubber previously held in place can slip. Devices incorporating rubber bushes are relatively expensive to manufacture partly because of the cost of the materials themselves, and partly because of the specialist equipment required to press the bushes into position and form a vulcanised bond between the resilient material (usually rubber) and the metal inner and outer sleeves of the bush. Failure of the vulcanised bond between the rubber bush and one or other of the metal sleeves can also lead to total failure of the clamp since, without the bond, no resilient force can be applied.